update docstrings

Author: jorisvandenbossche

pandas/core/strings/accessor.py

@@ -1245,8 +1245,9 @@ def contains(
             Flags to pass through to the re module, e.g. re.IGNORECASE.
         na : scalar, optional
             Fill value for missing values. The default depends on dtype of the
-            array. For object-dtype, ``numpy.nan`` is used. For ``StringDtype``,
-            ``pandas.NA`` is used.
+            array. For object-dtype, ``numpy.nan`` is used. For the nullable
+            ``StringDtype``, ``pandas.NA`` is used. For the ``"str"`` dtype,
+            ``False`` is used.
         regex : bool, default True
             If True, assumes the pat is a regular expression.
 
@@ -1378,8 +1379,9 @@ def match(self, pat: str, case: bool = True, flags: int = 0, na=lib.no_default):
             Regex module flags, e.g. re.IGNORECASE.
         na : scalar, optional
             Fill value for missing values. The default depends on dtype of the
-            array. For object-dtype, ``numpy.nan`` is used. For ``StringDtype``,
-            ``pandas.NA`` is used.
+            array. For object-dtype, ``numpy.nan`` is used. For the nullable
+            ``StringDtype``, ``pandas.NA`` is used. For the ``"str"`` dtype,
+            ``False`` is used.
 
         Returns
         -------
@@ -1422,8 +1424,9 @@ def fullmatch(self, pat, case: bool = True, flags: int = 0, na=lib.no_default):
             Regex module flags, e.g. re.IGNORECASE.
         na : scalar, optional
             Fill value for missing values. The default depends on dtype of the
-            array. For object-dtype, ``numpy.nan`` is used. For ``StringDtype``,
-            ``pandas.NA`` is used.
+            array. For object-dtype, ``numpy.nan`` is used. For the nullable
+            ``StringDtype``, ``pandas.NA`` is used. For the ``"str"`` dtype,
+            ``False`` is used.
 
         Returns
         -------
@@ -2586,7 +2589,7 @@ def count(self, pat, flags: int = 0):
 
     @forbid_nonstring_types(["bytes"])
     def startswith(
-        self, pat: str | tuple[str, ...], na: Scalar | None = lib.no_default
+        self, pat: str | tuple[str, ...], na: Scalar | lib.NoDefault = lib.no_default
     ) -> Series | Index:
         """
         Test if the start of each string element matches a pattern.
@@ -2598,10 +2601,11 @@ def startswith(
         pat : str or tuple[str, ...]
             Character sequence or tuple of strings. Regular expressions are not
             accepted.
-        na : object, default NaN
+        na : scalar, optional
             Object shown if element tested is not a string. The default depends
             on dtype of the array. For object-dtype, ``numpy.nan`` is used.
-            For ``StringDtype``, ``pandas.NA`` is used.
+            For the nullable ``StringDtype``, ``pandas.NA`` is used.
+            For the ``"str"`` dtype, ``False`` is used.
 
         Returns
         -------
@@ -2656,7 +2660,7 @@ def startswith(
 
     @forbid_nonstring_types(["bytes"])
     def endswith(
-        self, pat: str | tuple[str, ...], na: Scalar | None = lib.no_default
+        self, pat: str | tuple[str, ...], na: Scalar | lib.NoDefault = lib.no_default
     ) -> Series | Index:
         """
         Test if the end of each string element matches a pattern.
@@ -2668,10 +2672,11 @@ def endswith(
         pat : str or tuple[str, ...]
             Character sequence or tuple of strings. Regular expressions are not
             accepted.
-        na : object, default NaN
+        na : scalar, optional
             Object shown if element tested is not a string. The default depends
             on dtype of the array. For object-dtype, ``numpy.nan`` is used.
-            For ``StringDtype``, ``pandas.NA`` is used.
+            For the nullable ``StringDtype``, ``pandas.NA`` is used.
+            For the ``"str"`` dtype, ``False`` is used.
 
         Returns
         -------